1. Field of the Invention
The present invention relates to a method in which fine particles used in column fillers for fractionation/separation; microcapsules used in drugs, enzyme-containing capsules, cosmetics, perfumes, labeling/recording materials, adhesives, agricultural chemicals, or the like; and fine particles used in chemical reactions, solvent extractions, or the like; are stably produced in uniform sizes in a large amount. In addition, the present invention relates to a microchannel structure, microchannel structural body, and microchannel-structure laminated body for producing the above fine particles.
Priority is clamed on Japanese Patent Application No. 2006.237842, filed Sep. 1, 2006, the content of which is incorporated herein by reference.
2. Description of the Related Art
In recent years, the study using a microchannel structure, which includes a microchannel having a length of about a few centimeters and a width and depth in the range of submicrometers to a few hundreds of micrometers on a glass substrate of a few centimeters square, to carry out chemical reactions or productions of fine particles by introducing fluids to the microchannel has attracted attention. It has been suggested that efficient chemical reactions can be carried out using such microchannel structures due to the effects of a short intermolecular distance and a large specific interfacial area in the microspace therein (for example, refer to non-patent document 1).
In addition, it is possible to produce fine particles with an extremely uniform particle diameter by introducing two kinds of liquids having different interfacial tensions to a channel which has a joining section (for example, refer to non-patent document 2 and patent documents 1 and 2). Note that the term fine “particles” used here also includes fine particles, in which only the microdroplets or the surface of microdroplets are hardened (hereinafter referred to as “semi-hardened”), and the semi-solid fine particles having considerably high viscosity, other than the solid fine particles.
The above documents describe, for example, the T-shaped microchannel structure shown in FIG. 1, FIG. 2 which is an A-A′ cross section of FIG. 1, and FIG. 3 which is a B-B′ cross section of FIG. 1. As the figures show, the microchannel structure has a continuous-phase introduction inlet (2), a continuous-phase introduction channel (3), a dispersed-phase introduction inlet (4), a dispersed-phase introduction channel (5), a discharge channel (7), and a discharge outlet (8) on a microchannel substrate (I) and there is a joining section (6) where the introduced continuous-phase and dispersed-phase join hereinafter referred to as the “joining section”). By supplying solution while controlling the flow rates of dispersed phase and continuous phase using a T-shaped microchannel structure, in which the depth of each channel is 100 μm, the width of the introduction channel where the dispersed phase is introduced is 100 μm, and the width of the introduction channel where the continuous phase is introduced is 300 to 500 μm, it is possible to produce extremely uniform fine particles in the joining section. Additionally, it is also possible to control the particle diameter of the produced fine particles by controlling the flow volumes of dispersed phase and continuous phase.
However, his method has the following problems. That is, in this method, the flow volumes of dispersed phase and continuous phase are controlled by changing the respective supply rate thereof in order to control the size of the fine particles, and thus slight changes in the supply rates of dispersed phase and continuous phase lead to changes in particle size. This results in difficulties in controlling particle diameter stably and also in obtaining fine particles with uniform particle diameters.
Additionally, the chemical reactions in microchannels and studies to industrially produce fine particles have also been carried out while exploiting the characteristics of microspace such as the capability for cog out efficient chemical reactions due to the aforementioned effects of short intermolecular distance and large specific interfacial area in the microspace and the capability for producing fine particles with extremely uniform particle diameters by introducing two kinds of liquids having different interfacial tensions to a channel which has a joining section. In this case, due to the small size of the microspace, the amount of fine-particle production per unit time is inevitably small in a single microchannel structure. However, when it is possible to range numerous microchannel structures in parallel, the amount of fine-particle production per unit time can be increased while exploiting the aforementioned characteristics of microchannel structures (for example, refer to non-patent documents 3 and 4). As shown in non-patent document 3, attempts have been made to laminate the microchannel substrates having one microchannel by connecting them via a longitudinal hole which penetrates the common parts such as an inlet of reaction solutions and outlet of reaction products. It is said that chemical reactions and fine-particle production on an industrial scale while exploiting such characteristics of the microspace is possible by increasing the degree of integration of microchannel structures which are the minimum unit 2 dimensionally or by laminating the microchannel structures 3 dimensionally. However, it has conventionally been difficult to distribute fluids uniformly to the microchannels arranged in 2 or 3 dimensions, and thus improvements thereof have been required together with the further improvements in the degree of integration of microchannel structures.    [Patent document 1] Japanese Patent Publication No. 2975943    [Patent document 2] Japanese Patent Publication No. 3746766    [Non-patent docent 1] Hisamoto A. et al. “Fast and high conversion phase-transfer synthesis exploiting the liquid-liquid interface formed in a microchannel chip”, Chem. Commun., 2001, p 2662-2663    [Non-patent document 2] Nishisako T. et al. “Submerged production of microdroplets in microchannels” Proceeding of the 4th International Symposium Microchemist and Microsystems, p. 59, 2001    [Non-patent document 3] Kikutani et al. “High yield synthesis in microchannels using a pileup microreactor” Proceedings of the 3rd International Symposium Microchemistry and Microsystems, p. 9, 2001    [Non-patent document 4] Kawai A. et al. “Mass-production system of nearly monodisperse diameter gel particles using droplets formation in a microchannel”, μ-TAS 2002 vol. 1 p 368-370